Chemistry Class 12 NCERT Solutions: Chapter 2 Solutions Part 1

Q: 1. Calculate the mass percentage of benzene Equation and carbon tetrachloride Equation dissolved in Equation of carbon tetrachloride.

Ans:

Equation

Equation

Equation

Equation

Mass percentage of Equation

Equation

Equation

Equation

Alternatively,

Mass percentage of Equation

Equation

Q: 2. Calculate the mole fraction of benzene in solution containing 30% by mass in carbon tetrachloride.

Ans:

Let the total mass of the solution be Equation and the mass of benzene be Equation .

∴ Mass of carbon tetrachloride Equation

Equation

Molar mass of benzene Equation

Equation

∴ Number of moles of Equation

Equation

Molar mass of carbon tetrachloride Equation

Equation

∴ Number of moles of Equation

Equation

Thus, the mole fraction of Equation is given as:

Equation

Equation

Equation

Q: 3. Calculate the molarity of each of the following solutions:

(A) Equation of solution

(B) Equation Diluted to Equation

Ans:

Molarity is given by:

Equation

(A) Molar mass of Equation

Equation

Equation

Equation

Therefore, molarity Equation

Equation

(B) Number of moles present in 1000 ml of 0.5 M Equation

Equation

Equation

Therefore, molarity Equation

Equation

Q: 4. Calculate the mass of urea Equation required in making Equation molal aqueous solution.

Ans:

Molar mass of urea Equation

Equation

Equation Molar aqueous solution of urea means:

Equation of water contains Equation of urea

Equation of urea

That is,

Equation of solution contains Equation of urea

Therefore, Equation of solution contains Equation

Equation

Equation (Approximately)

Hence, mass of urea required Equation

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